mirror of
https://github.com/ivanizag/izapple2.git
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166 lines
4.1 KiB
Go
166 lines
4.1 KiB
Go
package izapple2
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import "fmt"
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/*
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Brain board card for Apple II
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See:
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http://www.willegal.net/appleii/brainboard.htm
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http://www.willegal.net/appleii/bb-v5_3.1.pdf
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The Brain Board card has 2 banks of ROM to replace the main ROM
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A 27c256 ROM (32k) is used, with the following mapping:
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0x0000-0x00ff: lower card rom maps to $Csxx
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0x1000-0x37ff: lower bank rom maps to $D000 to $F7FF
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0x3800-0x3fff: F8 lower bank rom maps to $F800 to $FFFF
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0x4000-0x40ff: upper card rom maps to $Csxx
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0x5000-0x77ff: upper bank rom maps to $D000 to $F7FF
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0x7800-0x7fff: F8 upper bank rom maps to $F800 to $FFFF
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DIP SWitches_
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1-ON : The range F8 can be replaced
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1-OFF: The range F8 is not replaced
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3-ON ,4-OFF: The motherboard ROM can be used
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3-OFF,4-ON : The motherboard ROM is always replaced
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5-ON ,6-OFF: The lower bank is used and mapped to Bank A
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5-OFF,6-ON : The lower bank is not used (A can be motherboards or uppers)
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7-ON ,8-OFF: The upper bank is used and mapper to bank B
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7-OFF,8-ON : The upper bank is not used (B can be motherboards or lowers)
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Switches and softswitches:
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Up, $COsO - SS clear: A bank selected
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Down, $COs1 - SS set: B bank selected
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*/
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// CardBrainBoard represents a Brain Board card
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type CardBrainBoard struct {
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cardBase
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isBankB bool
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isMotherboardRomEnabled bool
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dip1_replaceF8 bool
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dip34_useMotherboardRom bool
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dip56_lowerInA bool
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dip78_upperInB bool
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rom []uint8
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}
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func newCardBrainBoardBuilder() *cardBuilder {
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return &cardBuilder{
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name: "Brain Board",
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description: "Firmware card for Apple. It has two ROM banks",
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defaultParams: &[]paramSpec{
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{"rom", "ROM file to load", "<internal>/wozaniam_integer.rom"},
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{"dips", "DIP switches, leftmost is DIP 1", "1-011010"},
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{"switch", "Bank selected at boot, 'up' or 'down'", "up"},
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},
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buildFunc: func(params map[string]string) (Card, error) {
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var c CardBrainBoard
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var err error
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bank := paramsGetString(params, "switch")
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if bank == "up" {
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c.isBankB = false
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} else if bank == "down" {
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c.isBankB = true
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} else {
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return nil, fmt.Errorf("invalid bank '%s', must be up or down", bank)
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}
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dips, err := paramsGetDIPs(params, "dips", 8)
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if err != nil {
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return nil, err
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}
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c.dip1_replaceF8 = dips[1]
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if dips[3] == dips[4] {
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return nil, fmt.Errorf("DIP switches 3 and 4 must be different")
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}
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if dips[5] == dips[6] {
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return nil, fmt.Errorf("DIP switches 5 and 6 must be different")
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}
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if dips[7] == dips[8] {
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return nil, fmt.Errorf("DIP switches 7 and 8 must be different")
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}
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c.dip34_useMotherboardRom = dips[3]
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c.dip56_lowerInA = dips[5]
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c.dip78_upperInB = dips[7]
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romFile := paramsGetPath(params, "rom")
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data, _, err := LoadResource(romFile)
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if err != nil {
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return nil, err
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}
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if len(data) != 0x8000 {
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return nil, fmt.Errorf("the ROM file for the Brainboard must be 32k")
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}
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c.isMotherboardRomEnabled = true
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c.rom = data
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c.romCxxx = &c
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return &c, nil
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},
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}
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}
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func (c *CardBrainBoard) updateState() {
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isMotherboardRomEnabled := c.dip34_useMotherboardRom &&
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((!c.dip56_lowerInA && !c.isBankB) || (!c.dip78_upperInB && c.isBankB))
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if isMotherboardRomEnabled && !c.isMotherboardRomEnabled {
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fmt.Print("ROM: main")
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c.a.mmu.inhibitROM(nil)
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} else if !isMotherboardRomEnabled && c.isMotherboardRomEnabled {
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fmt.Print("ROM: brain")
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c.a.mmu.inhibitROM(c)
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}
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c.isMotherboardRomEnabled = isMotherboardRomEnabled
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}
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func (c *CardBrainBoard) assign(a *Apple2, slot int) {
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c.addCardSoftSwitchRW(0, func() uint8 {
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c.isBankB = false
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c.updateState()
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return 0x55
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}, "BRAINCLEAR")
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c.addCardSoftSwitchRW(1, func() uint8 {
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c.isBankB = true
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c.updateState()
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return 0x55
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}, "BRAINSET")
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c.cardBase.assign(a, slot)
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c.updateState()
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}
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func (c *CardBrainBoard) translateAddress(address uint16) uint16 {
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if c.isBankB {
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return address - 0xc000 + 0x4000
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} else {
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return address - 0xc000
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}
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}
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func (c *CardBrainBoard) peek(address uint16) uint8 {
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return c.rom[c.translateAddress(address)]
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}
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func (c *CardBrainBoard) poke(address uint16, value uint8) {
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// Nothing
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}
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func (c *CardBrainBoard) setBase(base uint16) {
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// Nothing
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}
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